Test for Cations

How is a flame test performed?

A nichrome wire is cleaned with dilute HCL, dipped in the sample and placed a flame

Colour for lithium

Crimson

Colour for sodium

Yellow

Colour for potassium

Lilac

Colour for calcium

Yellow/ red

Colour for copper

Green

What happens if there is a mixture of compounds?

The colours will mix or one will be masked by the other

What happens when ions are mixed with sodium hydroxide?

A precipitate is formed

Colour of aluminium precipitate

White and the precipitate dissolves in excess NaOH

Colour of calcium precipitate

White

Colour of magnesium precipitate

White

Colour of copper (II) precipitate

Blue

Colour of iron (II) precipitate

Green

Colour of iron (III) precipitate

Brown

What must be done to calcium and magnesium after being tested with NaOH?

Further testing via flame test